Method for spinning filaments which have been regenerated from a solution of cuprammonium cellulose and filaments produced thereby

ABSTRACT

A METHOD FOR SPINNING CUPRAMMONIUM YARNS IS DISCLOSED IN WHICH THE FILAMENTS, AS THEY EMERGE FROM THE SPINNERET ARE CONTACTED BY A DOWNWARD FLOW OF A COAGULATION LIQUOR (E.G. WATER) WHOSE TENSION IS ADJUSTED TO BE VIRTUALLY ZERO, THEN THE FILAMENTS PASS THROUGH A SECOND AREA IN WHICH THE FILAMENTS ACQUIRE A SUBSTANTIAL TENSION DUE TO THEIR FREE FALLING WHILE THEIR DIAMETER IS SUBSTANTIALLY REDUCED, WHEREAFTER THE FILAMENTS ARE PASSED THROUGH A THIRD WHERE THEY ARE CONTACTED BY ANOTHER DISCRETE STREAM OF COAGULATION LIQUOR TO COMPLETE THE COAGULATION. THUS THE TENSION IS RAISED TO THE EXPECTED   FINAL DRAWING VALUE AND THE FILAMENTS CAN NOW BE REGENERATED IN AN ACIDIC BATH (E.G. DILUTED H2SO4).

March 19, 1974 O. GALLINA METHOD FOR SPINNING FILAMENTS WHICH HAVE BEEN REGENERATED FROM A SOLUTION OF CUPRAMMONIUM CELLULOSE AND FILAMENTS PRODUCED THERE BY Filed Sept. 10, 1971 \fi la! H 32 2' 25 26 17 ORESTE GALL \NA ATTORNEYS United States Patent C) 3,798,297 METHOD FOR SPINNING FILAMENTS WHICH HAVE BEEN REGENERATED FROM A SOLU- TION F CUPRAMMONIUM CELLULOSE AND FILAMENTS PRODUCED THEREBY Oreste Gallina, Stresa, Italy, assignor to Bemberg S.p.A., Milan, Italy Filed Sept. 10, 1971, Ser. No. 179,415 Claims priority, application Italy, Sept. 22, 1970, 30,065/ 70 Int. Cl. D01d 5/14 US. Cl. 264-181 12 Claims ABSTRACT OF THE DISCLOSURE A method for spinning cuprammonium yarns is disclosed in which the filaments, as they emerge from the spinneret are contacted by a downward fiow of a coagulation liquor (e.g. water) whose tension is adjusted to be virtually zero, then the filaments pass through a second area in which the filaments acquire a substantial tension due to their free falling while their diameter is substantially reduced, whereafter the filaments are passed through a third area where they are contacted by another discrete stream of coagulation liquor to complete the coagulation. Thus the tension is raised to the expected final drawing value and the filaments can now be regenerated in an acidic bath (e.g. diluted H 50 This invention relates to a method for spinning filaments which have been regenerated from a solution of cuprammonium cellulose, wherein the solution is extruded through the holes of a spinneret, and the as-formed filaments are caused to pass through a vertical funnel, in contact with a descending flow of a coagulation liquor, whereafter the thusly coagulated filaments emerge from the funnel and are thoroughly regenerated in an acidic bath.

Such a method is conventional. According to the known method, the coagulation of the filaments in the coagulation funnel takes place gradually and uninterruptedly along the entire funnel length, from the instant where they come into contact with the descending stream of the coagulation liquor, that is, immediately below the spinneret, to the instant where they leave the funnel. During progress of said coagulation run, also the tension of the filaments is gradually raised under the entraining action of the descending stream of the coagulation liquor and, inasmuch as the filaments are in a plastic state, a drawing of the filaments is also experienced, which is conducive to a gradual thinning of the diameter along the funnel.

The device for carrying out the conventional method is generally composed by a vertical cylindrical body, on whose top end a spinneret supporting member rests, which houses a spinneret having extrusion holes, and from whose bottom end, as closed by a flange, the end portion of a frustoconical spinning funnel emerges, which is contained in said cylindrical body and having the end with the larger cross-sectional area placed slightly beneath the spinneret, an inlet duct for the coagulation liquor flow being provided in the lower portion of the cylindrical body.

The conventional method has the drawback that the spinning velocity of the filaments should be limited, as a rule, to about 60-70 meters per minute, since at a higher speed a rapid decay of the principal physical properties of the filaments is experienced, such as the tensile strength and the elongation at break. It is surmised that such a disadvantage is directly connected with the above mentioned phenomenon of uninterrupted and gradual coagulation of the filaments.

A method has now been found for spinning filaments 3,798,297 Patented Mar. 19, 1974 ice which have been regenerated from a cuprammonium cellulose solution, which makes it possible to achieve a spinning velocity which is at least twice the usual one.

The method according to the present invention consists in the fact that the as-extruded filaments are passed through a first incipient-coagulation area, where they enter into contact with a descending stream of a coagulation liquor whose rate of fiow (linear speed) is adjusted in such a way as to have a virtually non-existent tension of the filaments, whereas they substantially retain the diameter they had as they emerged from the spinneret, then they pass through a second area, consisting of a free space, through which the filaments are passed along with the coagulation liquor in a free fall thus acquiring a substantial tension, whereas their diameter is gradually reduced under the drawing action of the liquid fillet, and lastly the filaments are passed through a third area where they enter into contact with a new descending stream of coagulation liquor, whose rate of flow (linear speed) is adjusted so as to complete the coagulation of the filaments, whereas the tension thereof is raised up to the value which is desired for the final drawing of the filaments, whereafter the latter emerge from the funnel and are regenerated in an acidic bath. The rate of flow of the coagulation liquor, such as water, is adjusted in the first area consistently with the count of yarn which one desires to obtain and the number of filaments, but, at any rate, it should be such that the tension of the filaments is virtually nil. Such a result is easily achieved by reducing to low values the rate of flow of the coagulation liquor and by properly selecting the path of the filaments along with the path of the liquor stream. If the tension of the filaments is absent, the tension being notoriously due to the downward entraining action of the coagulation liquor flow, no drawing of the filaments is experienced through the entire first area so that the diameter of the filaments (or their transversal dimensions if they have a crosssectional shape other than circular) remain almost the same as they had in their as-extruded condition. Another consequence of the low rate of flow of the coagulation liquor is that the filaments remain enriched with cuprammonium liquor, so that the phenomenon of filament coagulation does not go beyond the initial stage, inasmuch as no elficient interchange between the coagulation liquor and the cuprammonium solution of cellulose can take place.

The first area is thus an area of incipient coagulation under a completely relaxed condition and is one of the distinctive elements of the present invention over the prior art.

In the second area, conversely, a partial drawing of the filaments is experienced. This drawing, as aforesaid, is due to the entraining action of the fillet of coagulation liquor which surrounds the filament bundle. Such a fillet is formed in the end portion of the first area by means of an appropriate shrinkage of the descending stream of the coagulation liquor, followed by the emersion in a free fall space in the second area. It should be noticed that also in the second area the coagulation of the filaments takes place to a slight degree only, inasmuch as the interchange between the coagulation liquor, such as water, and the components of the cuprammonium solution, is still limited to a slight amount. Thus, in the second area, a drawing of the filaments takes place, whereas the coagulation process substantially remains at its initial stage, and this is just another distinctive feature of the present invention over the prior art.

In the third area, where the filaments come into contact with a new descending stream of the coagulation liquor, the coagulation run is completed. To this end, the rate of flow is adjusted so as to achieve this result. In

general, such a rate of flow (linear speed) should be at least twice the rate of flow (linear speed) through the first area and the path of the filaments and the coagulation liquor therein will be selected accordingly.

The device for carrying out the method according to the invention comprises a vertical cylindrical body, on Whose top end rests a supporting member for a spinneret, in which a spinneret is mounted having extrusion holes, and from whose bottom end, closed by a flange, emerges the end portion of a frustoconical spinning funnel, contained in said cylindrical body, and is characterized in that the cylindrical body is internally partitioned into two sections by a flanged joint perpendicular to the axis of the cylindrical body, the upper section housing a first frustoconical spinning funnel, the bottom portion whereof penetrates through the flanged joint the lower section of the frustoconical body, where a second frustoconical spinning funnel is housed coaxially with the first funnel and spaced apart therefrom, the bottom portion of the second funnel emerging from the bottom end of the cylindrical body, separate induction ducts being provided for the individual coagulation liquor streams for each of the sections of said cylindrical body.

To the ends of the invention, the length of the spinning funnel of the upper section of the cylindrical body is, with advantage, from 1.5 to 2.5 times the length of the funnel of the bottom section of the cylindrical body.

The large diameter, that is the one corresponding to the top end, of the spinning funnel of the lower section of the cylindrical body, is, with advantage, from 1.2 to 2.5 times the larger diameter of the tunnel of the top section of the cylindrical body.

The distance between the end portion of the spinning funnel of the upper section of the cylindrical body and the upper portion of the spinning funnel of the bottom section of the cylindrical body, that is, the one which corresponds to the free space portion of the second area according to the method of this invention, is, with advantage, from 0.2 to 1.5 times the length of the spinning funnel of the bottom section of the cylindrical body.

In order that the invention may be more clearly illustrated, reference will now be had to the accompanying drawings which, however, should not be construed as a limitation. In the drawing, FIG. 1 shows a cross-sectional view of the device, whereas FIG. 2 gives an overall view thereof, in side elevation.

Having now reference to FIG. 1, the numeral 1 indicates the cylindrical body, which is preferably made of a transparent material. The joint composed by the two flanges 2 and 2' divides the cylindrical body into two sections, the top and the bottom section, respectively. On the top end of the cylindrical body 1 rests the spinneret supporting member 3, in whose chamber 4 the spinneret (not shown) is housed. The lower end of the cylindrical body is closed by the flange 5 and the counterflange 5'. In the top section of the cylindrical body 1 is housed the spinning funnel 6, also made of a transparent material, which is kept in position by the toroidal metal coil 7 and the gasket 8. The bottom end of the spinning funnel 6 enters, as can be seen, the bottom portion of the cylindrical body 1.

The bottom section of the cylindrical body 1 houses the spinning funnel 9, also made of a transparent material, which is kept in place with the aid of the gasket 10. The end portion of the spinning funnel 10 emerges from the lower end of the cylindrical body 1.

The coagulation liquor enters the top section of the cylindrical body 1 through the duct 11. Another stream of coagulation liquor enters the bottom section of the cylindrical body 1 through the duct 12.

Through the flange 2 a duct, 13, is formed, which establishes a communication between the bottom section of the cylindrical body 1 and the outside. The task of such a conduit is the following. Prior to starting the extrusion of the filaments, therespective streams of coagulation liquor are caused to enter the respective ducts 12 and 11, whereas the end portion of the spinning funnel 9 is temporarily closed, for example with a plug. As the coagulation liquor has completely filled the lower section of the cylindrical body 1, the duct 13 is closed, for example with a plug; meanwhile, also the top section of the cylindrical body 1 has been filled with coagulation liquor. (Air is discharged by lifting the flange 3.) At this stage, the end portion of the spinning funnel 9 and the duct 13 are opened, while the extrusion of the filaments is simultaneously started. The level of the coagulation liquor in the lower portion of the cylindrical body 1.

begins to lower and, as it reaches a few centimeters above the level which corresponds to the top portion of the spinning funnel 9, the duct 13 is plugged again, so that the level becomes stabilized in such a position.

The assemblage of the several component parts of the device is completed by the gaskets 14, 15, 16, 17, 18.

FIG. 2 shows how the two sections of the cylindrical body 1, as well as the supporting member 3 and the flanges, 2, 2 and 5, 5 are assembled together. To simplify the showing, the interior of the cylindrical body 1 has not been shown.

The upper section of the cylindrical body 1 is connected to the lower section by the joint composed by the flanges 2 and 2'. The tie rods 19, 20, 21, angularly spaced apart degrees from one another, together with the nuts 22, 23, 24, 25, 26 (the remaining nut cannot be seen) kept the supporting member 3 united to the upper section of the cylindrical body 1, which, in turn, is thus assembled with the bottom section. The latter, by the agency of the ties 27, 28, 29 and the nuts 30, 31, 32, 33, 34, 35 is kept assembled not only with the top section, but also with the flange 5 and the counterflange 5. It can now be easily understood that, by such an arrangement, the cylindrical body 1, the supporting member 3, the flanges 2 and 2', the flanges 5 and 5 and the spinning funnels 6 and 9 can be readily disassembled and reunited for the necessary cleaning operations.

The following example will further illustrate the method according to the present invention, even though it has not limiting value.

EXAMPLE A cuprammonium cellulose solution is spun with a device according to the present invention, having the following specifications:

Upper spinning funnel: larger diameter 30 mms., lesser diameter 6 mms., length 300 mms.

Lower spinning funnel: larger diameter 38 mms., lesser diameter 6 mms., length mms.

Distance between the upper and the lower funnel: 200 mms.

The number of monofilaments, corresponding to the number of the spinneret holes, was 45 and the final count of yarn was 67 detex. The speed at which the yarn was collected on the reel was 123 meters per minute. Water at the temperature of 48 C. was used as the coagulation liquor. The rate of flow of water in the upper spinning funnel was adjusted to 100 mls. per minute, whereas the rate of flow in the lower spinning funnel was adjusted to 500 mls. per minute.

As they emerged from the spinning device, and prior to being taken up on a reel in the form of a bundle, the filaments were completely regenerated through a sulphuric-acid containing bath.

A bundle of yarn so produced, after subsequent Wash ing, finishing, drying and conditioning operations, was subjected to the test of the principal physical and textile properties, by carrying out the necessary yarn samplings.

The following data were obtained:

tensile strength, g./dtex. 1.75 elongation at break 22% 5. which are fully acceptable values, if compared with those of yarns produced according to the conventional art.

What is claimed is:

1. In a method of spinning filaments which have been regenerated from a cuprammonium cellulose solution wherein the solution is extruded through the holes of a spinneret, treated with a coagulation liquid and subsequently regenerated in an acidic bath, said treating of filaments with a coagulation liquid comprises the steps of moving as-extruded filaments into a first portion of a vertical path and simultaneously engaging the filaments with a first surrounded confined flowing stream of coagu lation liquor moving downwardly with said filaments at a linear speed wherein tensioning of the filaments is substantially non-existent, next allowing the partially treated filaments and a portion of the liquor to free fall along a second portion of the vertical path and the filaments to acquire a substantial tension to efiect a drawing of the filaments with an associated gradual reduction in diameter of the filaments, and then moving the filaments into a third portion of the vertical path and simultaneously engaging the filaments with a second surrounding confined fiowing stream of coagulation liquor of a flow time sufiicient to complete the coagulation of the filaments and a linear speed to tension the filaments to that value which is desired for final drawing.

2. The method of claim 1 wherein the linear speed of said new stream of coagulation liquor is at least twice the linear speed of the first stream of coagulation liquor.

3. The method of claim 1 wherein the flow rate of said new stream of coagulation liquor is by volume five times the rate of fiow of the first stream of coagulation liquor.

4. The method of claim 1 wherein the length of said vertical path first portion is greater than the length of said vertical third portion.

5. The method of claim 1 wherein the length of said vertical path first portion is 1.5 to 2.5 times the length of said vertical path third portion.

6. The method of claim 1 wherein the length of said vertical path first portion is greater than the length of said vertical third portion and the length of said vertical path second portion being on the order of 0.2 to 1.5 times the length of said vertical path third portion.

7. Apparatus for forming and treating filaments which have been regenerated from a cuprammonium solution, said apparatus comprising an upstanding hollow body having upper and lower ends and an intermediate partition dividing said body into upper and lower sections, means at said upper end for mounting a spinneret of the type having a plurality of extrusion holes therethrough, a first frustoconical spinning funnel mounted within said upper section and extending through said partition into said lower section, said first spinning funnel having an upper end spaced closely below said spinneret support means for receiving as-extruded filaments, means sealing said first spinning funnel relative to said partition and said first spinning funnel having an open lower end opening into said lower section, means for supplying a first coagulation liquor to said upper section at a rate to con tinuously fill said first spinning funnel and to effect flow through said first spinning funnel at a linear speed wherein tensioning of filaments passing down through said first spinning funnel is substantially nonexistent, means at said body lower end closing the same and supporting in sealed relation a second frustoconical spinning funnel, said second spinning funnel extending down below said body lower end and having an upper end within said body lower section in spaced relation to said first spinning funnel lower end, means for supplying a second coagulation liquid to said body lower section to continuously fill said second spinning funnel while retaining an upper portion of said body lower section substantially between said spinning funnels free of liquid except that exiting from said first spinning funnel lower end and defining free fall area means cooperating with first coagulation liquor flowing out of said first spinning funnel for efiecting a substantial tensioning and drawing of filaments with an associated gradual reduction in diameter, said means for supplying said second coagulation liquor supplying said second coagulation liquor to said lower section at a rate to effect flow through said second spinning funnel at a speed to tension filaments to that value which is desired for final drawing.

8. Apparatus according to claim 7 wherein the length of said first spinning funnel is greater than the length of said second spinning funnel.

9. Apparatus according to claim 7 wherein the length of said first spinning funnel is from 1.5 to 2.5 times the length of said second spinning funnel.

10. Apparatus according to claim 7 wherein the length of said first spinning funnel is from 1.5 to 2.5 times the length of said second spinning funnel, and diameter of said second spinning funnel upper end is from 1.2 to 2.5 times the diameter of said first spinning funnel upper end.

11. Apparatus according to claim 7 wherein the length of said first spinning funnel is from 1.5 to 2.5 times the length of said second spinning funnel and the distance between said first spinning funnel lower end to said second spinning funnel upper end is from 0.2 to 1.5 times the length of said second spinning funnel.

12. Apparatus according to claim 7 wherein said linear speed of said second coagulation liquor is at least twice that of said first coagulation liquor lengthwise of said body.

References Cited UNITED STATES PATENTS 2,289,657 7/1942 Knehe et al 264-199 3,488,344 1/1970 Bifi et al 264-l8l 1,828,497 10/1931 Hartmann et a1. 264199 2,027,419 1/ 1936 Dreyfus 264-181 FOREIGN PATENTS 2,766 1/1970 Japan 264-180 442,059 1/ 1969 Japan 264-181 JAY H. WOO, Primary Examiner US. Cl. X.R. 

